Component.java 文件源码

@SuppressWarnings("unchecked")
public <T extends EventListener> T[] getListeners(Class<T> listenerType) {
    if (ComponentListener.class.isAssignableFrom(listenerType)) {
        return (T[]) getComponentListeners();
    } else if (FocusListener.class.isAssignableFrom(listenerType)) {
        return (T[]) getFocusListeners();
    } else if (HierarchyBoundsListener.class.isAssignableFrom(listenerType)) {
        return (T[]) getHierarchyBoundsListeners();
    } else if (HierarchyListener.class.isAssignableFrom(listenerType)) {
        return (T[]) getHierarchyListeners();
    } else if (InputMethodListener.class.isAssignableFrom(listenerType)) {
        return (T[]) getInputMethodListeners();
    } else if (KeyListener.class.isAssignableFrom(listenerType)) {
        return (T[]) getKeyListeners();
    } else if (MouseWheelListener.class.isAssignableFrom(listenerType)) {
        return (T[]) getMouseWheelListeners();
    } else if (MouseMotionListener.class.isAssignableFrom(listenerType)) {
        return (T[]) getMouseMotionListeners();
    } else if (MouseListener.class.isAssignableFrom(listenerType)) {
        return (T[]) getMouseListeners();
    } else if (PropertyChangeListener.class.isAssignableFrom(listenerType)) {
        return (T[]) getPropertyChangeListeners();
    }
    return (T[]) Array.newInstance(listenerType, 0);
}